1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
As an image forming apparatus for forming an image, an image forming apparatus has been known. The image forming apparatus includes a two component developer replacing means for automatically replacing a two component developer in a developing apparatus, an opening for releasing the inner pressure of the developing apparatus and a vent duct for discharging air to the outside from the apparatus.
The vent duct passes through a waste developer container for discarding a used developer in the two component developer replacing means, and a toner filter is provided in the waste developer container.
According to this configuration, air discharged from the opening of the developing apparatus is filtered through the filter provided in the waste developer container, and is discharged through the vent duct to the outside from the apparatus.
However, in such an image forming apparatus, plural developing units are connected with each other via a vent duct or a waste developer container. When the developing units are operated, the pressure within the developing units increases due to the heat generated by the operation of the developing units, the rotation of developer rolls or the like, so that toner-containing air in the developing units tends to flow to lower-pressured sections in the image forming apparatus. Accordingly, when both a developing unit that is in operation and a developing unit that is not in operation are present in the same time, air flows from the developing unit that is in operation to the developing unit that is not in operation through the waste developer container or the vent duct due to the difference in pressures therebetween. Therefore, the toner-containing air to be discharged through the toner filter flows into the developing unit that is not in operation, resulting in occurrence of problems such as color mixing.